York County, Pa. – When looking to fill up your tank, would you drive farther to pay more? Randy Hake's customers are doing just that, since he's the only gas station in York County, Pa., selling "pure" ethanol-free fuel.

"I get 20.1 miles to the gallon, in-town driving. I used to get 13," said Sue Cannon who drives 20 miles to Hake's from her home in Hanover, Pa.

Studies show straight gasoline gets 2 to 10 percent better gas mileage than fuel made with ethanol, an alcohol produced from corn. It costs about 20 cents more per gallon at the pump, but Cannon says paying more up front is worth it down the road. She started using "pure gas" five weeks ago, after paying $12,000 for repairs on her 2005 Nissan Pathfinder.

"I had to change two radiators and two transmissions," said Cannon, who blames the damage on ethanol.

Right now, gasoline sold at more than 95 percent of filling stations in the U.S. contains 10 percent ethanol, a blend known as E-10.

Ethanol was first added to gasoline 30 years ago. Bob Dinneen, CEO of the Renewable Fuels Association, says it's an American success story, utilizing fuel sources like corn, reducing our dependence on foreign oil and reducing gas prices by $1.09 a gallon in 2011.

“Ethanol is an American-made product," Dinneen said. "We are creating jobs here. We are creating economic opportunity here. We are lowering gasoline prices here, as opposed to a pure gasoline that is lining the pockets of regimes in parts of the world that don’t like us very much.”

Now, the ethanol debate is heating up.

The ethanol industry petitioned the Environmental Protection Agency to add 5 percent more ethanol to fuel, creating a mix known as E-15. The EPA recently approved it for use in cars made since 2001.

Proponents say E-15 will save drivers 5 cents more a gallon and is expected to be available as early as this summer.

However, a newly released two-year study suggests millions of cars and light trucks being driven today may not be able to handle the new fuel blend.

"Ethanol attracts water, and that can result in corrosion in the system," said Rayola Dougher from the American Petroleum Institute. "We're hitting what they're calling a blend wall, where you're required to use ever greater volumes of ethanol in the gas distribution system but it goes beyond what the cars are being designed for. And this is particularly an issue with E-15."

The study, sponsored by the oil industry group and automakers, tested eight engines found in millions of cars currently on U.S. roads. The study found two of the eight malfunctioned and suffered significant damage while fueled by E-15.

The U.S. Department of Energy, which tested E-15 on vehicles prior to the EPA's decision, disputes the study, calling it "unreliable and incomplete".

The American Petroleum Institute accuses the federal government of the same, and it is suing the EPA to force more research before E-15 becomes available at gas stations this summer. A decision is expected in June.